In the past decade, the concern of governments for ecology and environment has become one of the top, if not the top priority. In the United States, 80% of all trash is being landfilled, the remaining 20% being split between incineration and recycling. However, landfilling has its limits, and soon, incineration and recycling will become the best, if not the only way of disposing of trash.
Governments throughout the world have enacted legislation concerning the use and disposal of wastes, and it is likely that upcoming environmental laws will be more strict and rigid against any kind of pollution.
Accordingly, the great challenge of industries in almost every field is to keep on producing goods at reasonable costs, while meeting environmental criteria more strict and the plastic industry is no exception.
At present, many items manufactured from plastic materials are generally made of polyvinyl chloride (PVC). PVC is a versatile material, but has serious environmental drawbacks. Incineration of PVC produces chlorinated dibenzofurans, chlorinated dibenzodioxins, and hydrochloric acid gas. It is now of common knowledge that dioxins and furans have been linked to diseases such as immuno-system failure, cancer, and birth defects. Also, hydrochloric acid is a powerful corrosive substance, and when combined with atmospheric moisture, it significantly contributes to acid rain.
Since PVC materials also contain to, tic additives such as heavy metals used as stabilizers and plasticizers, disposal of these coverings by landfilling is highly undesirable because these additives are slowly leached by water, and thus dispersed in the soil. Most of these stabilizers are considered carcinogenic.
The use of these stabilizers has also led to bans on PVC incineration, and has raised questions concerning the acceptance of products containing PVC that could eventually end up in waste.
Many governments have already banned either production and/or importation of PVC materials in their countries and this has lead to a race between manufacturers to find a non-toxic substitute for PVC which can be welded at high frequency. This represents a tremendous task. Plastic manufacturers are investing important amounts of money at every level to develop a new thermoplastic material suitable for high frequency welding which would overcome all the serious drawbacks of PVC. In this research, many requirements must be met.
The new thermoplastic material must be produced competitively while meeting the desirable performance requirements. The process leading to the final product should be susceptible to efficient continuous production operations. The thermoplastic material should also be strong enough to withstand stretching without the creation of holes, tears, or non-uniform zones of stretching.
The processing of PVC or similar materials into sheets involves extremely expensive machinery and the challenge is to develop a thermoplastic material which can, on one hand, be processed into sheets with existing machinery, and on the other hand, be converted into consumer goods by using the currently available machinery, especially such machines which use high frequency welding methods. Generally, the PVC materials are welded by high frequency, and the replacing thermoplastic material must also be capable of being welded by high frequency in any subsequent operation, and that represents the key step leading to the final consumer good.
Finally, the thermoplastic material should be easily recyclable, or in the alternative, should cause little damage to the environment when incinerated. The present invention fulfills all the above requirements.